State machines:
teach your PLC where it is.
A PLC re-runs your whole program every few milliseconds, and it has no idea 'where' a sequence is unless you tell it. This module gives your code a memory of its own progress. You build the CASE step engine first, then add transitions with entry/exit actions, timeout and fault states, and finally a reusable sequencer FB. There are six chapters with a live widget in each, and the last one runs a real CIP wash cycle.
From flag soup to clean steps
🍝 the moment a sequence has more than two stages, loose booleans turn into spaghetti. One state variable and a CASE block replace a dozen interlocking flags with one obvious 'where am I now'.
How real machines run
🏭 every batch tank, palletiser, CIP skid and start-up sequence on a plant floor is a state machine underneath. Learn the pattern once and you can read (and write) the sequencing logic in almost any control system.